import java.util.Scanner;


public class Rec {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();

        int ret = factor(n);
        System.out.println(n+"阶乘是"+ret);
    }

    public static int factor(int n) {

        if (n == 1) {
            return 1;
        }
        int ret = n * factor(n-1);
        return ret;
    }
}
